when
Two kinds of chemical change which investigated side by side : 1. Combustion
2. The calcination of metals
The effect of heat on substances :
“the metals, except gold and silver, were found to change when
heated in open crucibles and to leave a dross, which was called a
calx (lime)”
The explanations (16th century) :
“some kind of „soul‟ escaped from the metal, or the matter became
denser, or some kind of acid was absorbed from the fire, or the fire possesssed weight and was absorbed by the metal in forming the
calx”
boyle
Boyle (Robert Boyle) was born in Lismore Castle (Ireland) in January, 25th
1627 and died in December, 31th 1691 in London (England).
Boyle describes of the element on his book, “the sceptical chymist”. In
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Boyle has been called the founder of modern chemistry for three reason :
1. He realized that chemistry is worthy of
study for its own sake and not merely as an aid to medicine or as alchemy
2. He introduced a rigorous experimental method into chemistry
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Boyle‟s definition of an element is as follow (Sceptical Chymist) :
“I mean by Elements certain Primitive and Simple, or perfectly
unmingled bodies; which not being made of any other bodies, or of
one another, are the Ingredients of which all those call‟d perfectly
mixt Bodies are immediately compounded and into which they are
ultimately resolved”
Boyle‟s Law (1662 and sometimes called Boyle-Mariotte‟s law) :
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On his book, General History of the Air, Boyle concluded that air composed of at least three parts :
1. Vapours from water and living animals
2. A very subtle emanation from the earth‟s magnetism, producing the sensation of light
3. A fluid, compressible and dilatable, having weight and able to refract light
Boyle‟s experiment with gunpowder is interesting :
When gunpowder dropped upon the heated plate in vacuum, the
powder burned slowly but did not explode :”we saw a pretty broad
blue flame like brimstone, which lasted so long as we could not but
wonder at it”
Boyle remarked that the glow gradually disappears when phosporus is
shut up in a glass tube and hence he concluded that “the air had
some vital substance preyed upon or else tamed by the fumes of
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On his book, New Experiment to Mae Fire and Flame Stable and
Ponderable (1673), Boyle concluded that air had a weight. Boyle
found that 8 oz. of block tin when heated in an open flask increased in weight by 12 grain. Then he explained that the increase in weight was gained by the operation of fire on the metal.
On another books, Experiment ... Touching Colour (1664) and The
Reflectionss upon the Hypothesis of Alcali and Acidum (1675), Boyle
gives some general properties of acids and alkalis, such as the sour taste of acids, their action as solvents, their action on vegetable
colours (indicators) and their reaction with alkalis (the formation of a neutral salt). On this books, Boyle mentions the green colour
